The present disclosure relates to the subject matter contained in Japanese Patent Application No. 2002-064314 filed on Mar. 8, 2002, which is incorporated herein by reference in its entirety.
1. Field of the Invention
The present invention relates to a shielded wire.
2. Description of the Related Art
For example, an inverter device mounted on an electric vehicle is connected a plurality of wires extending from other devices. JP-A-11-26093 discloses a structure for connecting these shielded wires. In this structure, attachment holes are formed in a shield case, which receives the inverter device therein, and device-side terminals disposed in the shield case face to the attachment holes, respectively. Then, connectors each fixedly secured to an end portion of the wire are inserted into the attachment holes, respectively to connect the device-side terminals with the connectors.
Incidentally, this kinds of shielded wire has a shield layer to prevent electrical noises generated from the inverter device or the like from leaking to the exterior. Generally, a flexibly-deformable tubular member, which is called a braided conductor, is used as this shielding layer. To connect the easily-deformable braided conductor with the shield case, a shield shell having high rigidity is fitted to an outer peripheral surface of a distal end portion of each braided conductor to attach the shield shell to the shield case in contact manner.
Here, to reduce the time and labor required for an assembling operation in a case of shielding a plurality of wires, there may be proposed a method in which these wires are collectively enclosed in a braided conductor, a single shield shell is fitted to an end portion of the braided conductor, and this shield shell is connected with a shield case. With this method, there is achieved an advantage that the time and labor required for the assembling operation is reduced since the only one shield shell is used.
In this kind of shielded wires, however, the distal end portions of the wires must be spaced apart from one another for insulating purposes, and in this connection the shield shell need to have a large size. Therefore, when fitting the shield shell to the end portion of the braided wire, the end portion of the braided wire must be expanded wide. As a result the meshes of the braid become coarse, which invites a problem that the shielding performance can be lowered.
This invention has been made under the above circumstances. An object of the invention is to provide a shield connector device capable of preventing from lowering the shielding performance.
The above object has been achieved by a shielded wire according to a first aspect of the invention. The shielded wire includes an insulated wire, a tubular braided conductor, a shield shell, and an auxiliary shielding layer. The tubular braided conductor encloses the insulated wire. The shield shell is disposed at an end portion of the insulated wire and has a larger diameter than the braided conductor. The auxiliary shielding layer is formed on an outer peripheral surface of the insulated wire in the vicinity of the shield shell where meshes of the braided conductor are coarse. The braided conductor is connected to the shield shell with an opening end portion of the braided conductor being expanded. The auxiliary shielding layer is electrically connected to the braided conductor.
According to a second aspect of the invention, in the shielded wire of the first aspect, the shield shell has an inner shell and an outer shell. The open end portion of the braided conductor is held between the inner shell and the outer shell so that the braided conductor is electrically connected to the shield shell.
According to a third aspect of the invention, the shielded wire of any one of the first and second aspects, further includes a fastening member. The fastening member holds the braided conductor from the outside thereof so that the braided conductor contacts the auxiliary shielding layer.
According to a fourth aspect of the invention, in the shielded wire according of the third aspect, the fastening member is disposed at a position corresponding to one end portion of the auxiliary shielding layer opposite to the other end portion thereof located in the vicinity of the shield shell.
According to a fifth aspect of the invention, in the shielded wire of any one of the first and third aspects, the auxiliary shielding layer is a heat-shrinkable tube made of a conductive resin, which covers on the insulated wire and is heated to shrink.
According to a sixth aspect of the invention, in the shielded wire of any one of the first and third aspects, the auxiliary shielding layer is a adhesive metal tape, which is wound on the insulated wire.
For example, when a braided conductor is used for shielding a cable connecting a power motor to an inverter device, this braided conductor is connected via a shield shell to a shield case containing the inverter device. In this condition, meshes of the braided conductor in the vicinity of an open end thereof are made coarse so that the shielding performance is lowered. Therefore, there is a fear that electrical noises generated from the inverter device leak through these meshes.
On the other hand, in the first aspect of the present invention, an auxiliary shielding layer is formed on an outer peripheral surface of the insulated wire in the vicinity of the shield shell where meshes of the braided conductor are coarse. In addition, the auxiliary shielding layer is electrically connected to the braided conductor. Therefore, electrical noises will not leak to the exterior through the meshes of the braided conductor and are grounded to the shield case via the auxiliary shielding layers and the braided conductor.
According to the third aspect of the invention, the auxiliary shielding layer on the insulated wire and the braided conductor are held in contact. Furthermore, even when an external force such as vibrations is applied, this contacted condition will not be affected. Therefore, the shielding is positively effected.
According to the fifth aspect of the invention, when the auxiliary shielding layer is formed of the heat-shrinkable tube, it is tightly mounted on the insulated wire. There will not be encountered a disadvantage that this tube is displaced or disengaged even upon application of an external force such as vibrations. Therefore, the more positive shielding effect is achieved.
According to the sixth aspect of the invention, when the auxiliary shielding layer is formed of the metal tape, this construction can be used in a general-purpose manner for a variety of insulated wires having different diameters and lengths.